Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Thermomechanical characterization of a Cu-Al-Mn shape memory alloy processed by investment casting
Submission Author:
Railson de Medeiros Nóbrega Alves , PB
Co-Authors:
Railson de Medeiros Nóbrega Alves, Paulo César Sales da Silva, RODINEI MEDEIROS GOMES, Danielle Cavalcante, Carlos Jose de Araujo
Presenter: Carlos Jose de Araujo
doi://10.26678/ABCM.COBEM2023.COB2023-0242
Abstract
Shape Memory Alloys (SMA) are a unique class of metallic alloys that have the ability to recover their shape when subjected to large deformations and an appropriate thermal cycle. These alloys are known to be smart materials, meaning they have the ability to mechanically respond to a non-mechanical stimulus. SMAs exhibit two differentiated functional properties: Superelasticity (SE), the ability to recover large deformations (around 8%), and the Shape Memory Effect (SME), which allows for the recovery of an apparently plastic deformation by heating above a characteristic temperature. Cu-Al based SMAs have the advantage of being made from relatively inexpensive materials and using conventional metallurgical processes, such as melting without a protective atmosphere, making this group of alloys an attractive alternative to Ni-Ti and justifying its use in some applications. For these binary alloys, transformation temperatures are high and can be manipulated with the addition of a third element, such as Mn, Ni, and Be. Therefore, this work aims to characterize the thermomechanical behavior of a Cu83-Al12-Mn5 (%wt) SMA. The electric arc melting was used in the production of the bulk SMA, which was then remelted and poured into ceramic molds by a centrifugation investment casting process. The phase transformation temperatures of the Cu-Al-Mn SMA were determined using Differential Scanning Calorimetry (DSC), which exhibits SME behavior at room temperature. Quasi-static tensile tests were performed under isothermal temperatures to determine the mechanical properties, such as stresses for the forward and reverse phase transformations and residual strains. A Dynamic Mechanical Analyzer (DMA) was used to determine the material's elastic modulus and damping capacity as a function of temperature. To evaluate the phases present in the alloy, X-ray diffraction (XRD) was performed, followed by an optical microscopy analysis to evaluate the grain structure. It was observed that the Cu-Al-Mn SMA has a mechanical strength and maximum deformation of about 425 MPa and 11,5%, respectively, at 30 oC. However, in the superelastic regime at 150 °C, the material can be loaded at 600 MPa and 7% deformation without apparent failure.
Keywords
Shape Memory Alloys, Cu-Al-Mn alloys, Thermomechanical Behavior, Shape Memory Effect., investment casting
